Biogeography is one of the most fascinating topics in all of natural history. The basic question is simple: Where do organisms live? But every subsequent question adds a new layer of complexity: Do they live there all the time? Why do they live there? Are there patterns that emerge when we look at groups of organisms? Are there strange discrepancies that don't fit the pattern? How small of an area can we map, and how finely? In this talk, we'll explore broad bioregions of the United States from the perspective of mushrooms (which sometimes align with bioregions of plants and animals... but not always!). From the chilly and damp temperate rainforests of the Pacific Northwest to the subtropical hardwood hammocks of Florida; from the arid interior deserts to the alpine crest of the Rocky Mountains, we'll take a tour of some of the country's distinct macrofungal communities and ask ourselves questions about time, space, and evolution.